1. Field of the Invention
The present invention generally relates to data processing and more particularly to ensuring coherency between queries and data definition frameworks.
2. Description of the Related Art
Databases are computerized information storage and retrieval systems. A relational database management system is a computer database management system (DBMS) that uses relational techniques for storing and retrieving data.
Regardless of the particular architecture, in a DBMS, a requesting entity (e.g., an application, the operating system or a user) demands access to a specified database by issuing a database access request. Such requests may include, for instance, simple catalog lookup requests or transactions and combinations of transactions that operate to read, change and add specified records in the database. These requests are made using high-level query languages such as the Structured Query Language (SQL). Illustratively, SQL is used to make interactive queries for getting information from and updating a database such as International Business Machines' (IBM) DB2, Microsoft's SQL Server, and database products from Oracle, Sybase, and Computer Associates. The term “query” denominates a set of commands for retrieving data from a stored database. Queries take the form of a command language that lets programmers and programs select, insert, update, find out the location of data, and so forth.
One of the issues faced by data mining and database query applications, in general, is their close relationship with a given data definition framework (e.g., a relational database schema) which describes a particular arrangement of data. Data definition frameworks include database metadata such as tables and columns, and XML documents such as schemas and data type definitions (DTD). This close relationship with a given data definition framework makes it difficult to support a requesting entity as changes are made to the corresponding underlying data definition framework. In particular, queries that are premised upon an outdated version of a data definition framework may no longer return intended results, or may simply return an error.
Therefore, what is needed is a method for ensuring coherency between queries premised upon a particular data definition framework and the data definition framework currently overlying the data to be accessed.